A drain board installing device that can install a drain board in the ground without an anchor plate is disclosed in the cited reference 1 (Korean Patent No. 622233) and the cited reference 2 (Korean Patent No. 720079).
Such a conventional drain board installing device without an anchor plate includes a leader 102, a drain casing clamp holder 103, a drain casing 104, and a reel device 106, as illustrated in FIG. 1, wherein the drain casing 104 is provided with a drain board temporary clamp device 46 at the end.
The leader 102 is installed in a main body of the drain board installing device so as to adjust its angle, and the drain casing clamp holder 103 is provided to ascend and descend along an up and down direction of the leader 102.
The drain casing clamp holder is fixed to a pulley 144 where wire 133 is wound, and thus is driven indirectly by a hydraulic cylinder 145. Alternatively, the drain casing clamp holder may be provided to insert or take the drain casing into or out of the ground by using other method.
The drain casing 104 is provided with a through hole 108 therein, and is provided with a drain board temporary clamp device 46 in its lower body.
The conventional drain board temporary clamp device 46, as illustrated in FIG. 2, includes a rod shaped support 47 supporting a drain board 105 descended to the lower end through the through hole 108, an arm 48 provided to space apart from the support at a certain distance (0.5 m˜1 m) toward a vertical downward direction from a lower opening of the drain casing, and a spring device 50 advancing and retracting the arm.
The spring device 50 is provided to insert a spring 51 into a moving path 52 of the arm formed inside the spring device and elastically support the arm through the spring 51.
The end of the drain board 105 supplied into the through hole 108 of the drain casing is fixed between the lower opening of the drain casing and the support 47 of the drain board temporary clamp device 46. As illustrated in FIG. 3, the drain casing 104 where the drain board 105 is fixed to the end is inserted into the ground through a drainage layer 11, a cover layer 10, and a weak ground 9, wherein the drainage layer 11 is installed for safety and drainage of the drain board installing device. Since earth and sand pile up when the drain casing 104 inserted into the ground is taken out of the ground, the arm 48 of the temporary clamp device and the support 47 push the end of the drain board until the end of the drain board is fixed to the ground.
After the drain casing is taken out of the ground, if a part C of the drain board exposed on the ground is cut, the drain board 105 only remains in the ground. Since the drain board 105 remaining in the ground drains the water of the weak ground layer through the drainage layer 11 in accordance with load pressure of upper materials and capillary phenomenon, the drain board 105 acts to enhance a support power of the weak ground.
However, the aforementioned drain board installing device 101 has a problem as follows, That is, fine-grained earth water flows into the moving path 52 of the arm through a part marked with a circle of FIG. 2, i.e., a part where the arm 48 slides in an airtight state when the drain board installing device 101 inserts the drain casing into the ground. In this case, the moving path of the arm is filled with the fine-grained earth water. If the drain board installing device 101 is used for a long time, a function of the drain board temporary clamp device 46 is remarkably deteriorated or damaged.
Also, when the drain board temporary clamp device is out of order, a problem occurs in that it is inconvenient to repair and detach the drain board temporary clamp device.
(Cited Reference 1)
Korean Patent No. 622233
(Cited Reference 2)
Korean Patent No. 720079